Electromagnetic radiation proof igniting device



June 25, 1963 w. D. GREENLEES 3,094,932

ELECTROMAGNETIC RADIATION PROOF IGNITING DEVICE FiledJuly 15, 1960 IN 44 \g 24 22 3| 32 2| I/Ai -4262 3 33 v/11114 43 35 INVENTOR. WILLIAM D. GREENLEES United c 3,894,932 iatented June 25, 1963 3,094,932 ELECTROMAGNETIC RADIATION PROOF IGNITING DEVICE William D. Greenlees, 2321 Saddle Tree Drive, Alexandria, Va.

Filed July 15, 1960, Ser. No. 43,255 12 Claims. (Cl. 102-28) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relatesto the shielding of an electrically initiated detonator from electrostatic or electromagnetic energy such as could actuate the detonator.

Detonators actuated by the closing of a switch either simultaneously with an larming operation or at some time interval after an arming operation have been known to be initiated by radio or radar waves. This inadvertent actuation of the detonator has made it necessary to provide between the detonator and the missile fuel or whatever the detonator actuates, a safety in the form of a shield or moveable plate which is moved to an out of way position by the arming mechanism. The possibility of inadvertent actuation of the detonator however, after the arming operation and before firing has made this type of installation dangerous and unreliable.

The object of the present invention is to so mount a detonator that it is shielded from stray waves of electrostratic or electromagnetic energy which might actuate the detonator.

Another object of the invention is to completely enclose the detonator within a metal housing, at least one side of which is rupturable to admit a con-tact making rod.

A further object of the invention is to provide a mechanism having a housing piercing, solenoid operated, contact rod which will arm the detonator prior to firing when an interval between arming :and firing is desired.

Yet another object is to provide a mechanism which is controlled from :a single control switch and will arm and fire in rapid succession and with no appreciable delay between the arming and firing.

A still further object of the invention is the provision of a housing for the detonator which is impervious to spurious electrostatic and electromagnetic energy Waves and which is easily broken by a mechanical, solenoid-- operated contact rod.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a longitudinal section of the detonator land solenoid mechanism employing the present invention; and

FIG. 2 is a similar view of a modification of the mechanism illustrated in FIG. 1.

Referring to the drawing wherein like parts are designated by like numerals throughout the views thereof, the invention is illustrated in its preferred form in FIG. 1 while a modification of the invention, in which the wiring is different and some small parts changed, is illustrated in FIG. 2.

With particular attention to FIG. 1 a housing 12 preferably of cylindrical form is threaded interiorly at 13 to receive a metallic nipple 14. The nipple 14 is interiorly threaded to receive a detonator 17 which is completely housed Within the nipple. An end cap 18 having a central opening temporarily closes the end of the nipple.

For attachment to a missile or any structure to be detonated, the cap 18 may be removed and the threads 15 of the nipple threaded into a hole provided for it.

The detonator 17 consists of :a threaded hollow plug with an insulator sleeve 19 housing a contact plug 21 having a conical depression 20 at one end which extends beyond the hollow plug, and terminating at the other end even with the insulator sleeve to form a charge carrying chamber 22 at the threaded end of the hollow plug. An igniter wire 23 connected at its mid point to the contact plug 21 and with each end portion extending along the side of the charge carrying chamber and connected to the side of the chamber, grounding the contact. This forms two substantially oppogite short sections of wire which upon the circuit being closed glow and ignite the charge carried in the chamber 22.

Between the end cap 18 and the end of the nipple 14 a metallic disk 24 covers the charge carrying chamber 22 and seals one end of the nipple. The other end of the nipple is closed by a second metallic disk 26 which is held against the housing 12 by the nipple 14, and forms a complete housing with the nipple 14 and the disk 24 for the detonator, which shields the detonator from electrostatic or electromagnetic energy. The disks 24 and 26 are made of an easily rupturable material such as aluminum.

Located in the housing, an insulating sleeve 27 Sup ports a solenoid 28 which has a moveable core 29. The core 29 carries an attached pin 31, journaled in plate 30 and pointed at its forward end 32, while back of the pointed end, it is recessed to receive an insulating sleeve 33 which insulates the forward portion of the pin, except for the pointed end 32 from external contact. The pin forms one contact 35 of a circuit which includes a battery 34, a switch 36 and a ground connection at 37. The ground connection is made to the nipple 14 and through the nipple and the detonator 17 to the ends of the wire 23 and the plug 21 to which the wires are attached at the midpoint thereof.

The solenoid has its own circuit including a battery 38, and a switch 39. The closing of the switch 39 energizes the solenoid, moving the core 29 and its attached pin toward the detonator.

Located in the cylindrical housing 12 a coil spring 41 bears against an enlarged head 42 of the core 29 and normally holds the core yieldably in a retracted position. A screw 43 threaded in the housing 12 contacts the head 42 and provides an adjustable stop which limits the movement of the core, the screw being locked in adjusted position by a nut 44.

The operation of the embodiment of the invention as illustrated in FIG. 1 may be briefly described as follows:

Switch 39 is closed and the solenoid energized. The resulting movement of the core drives the pointed end of the pin 31 through the metal disk 26 and into engagement with the conical depression of the contact plug 21 to arm the detonator. Shorting of the pin 31 with the metal disk 26 is prevented by the sleeve 33. Now closing of the switch 36 energizes the circuit through the pin 31, the contact plug 21 and causes the wires 23 to heat sufficiently to glow. This ignites the explosive material 46 carried in the chamber 22, ruptures the disk 24 and ignites whatever charge to which it is connected.

Referring to FIG. 2 an embodiment of the invention which differs from that of FIG. 1 in detailed construction is illustrated.

The detonator used in this embodiment of the invention is the same as that of detonator 17 and is so numbered, except that the conical depression is replaced with a spring contact 51 formed of a spring material and attached to the contact plug 21 at its midpoint with each 3 end in the form of a semi-circle to provide a contact which is slightly spaced initially from the end of the contact plug. The nipple 14, end cap 18 and disk 24 are similar to those of FIG. 1 and so numbered.

The disk 52 at the end of the housing is of a laminated construction with a thin sheet of metal, 53, preferably aluminum, between sheets 54 of an insulating medium.

The housing 56 is substantially the same as housing 12 having an additional well 57, which could be included in the invention illustrated in -FIG. 1 with its function. The well is traversed by a pin 58 which supports a spring pressed weight 59 formed with an otfset finger 61 normally bearing against the underside of the head 42 of the core. The weight is substantially of a mass equal to that of the core and provides a safety against accidental movement of the core and its contact pin, should the structure to which the housing and detonator are attached be accidentally dropped. With the weight being su' stantially the same mass as the core, movement of the core toward the detonator would be resisted by the finger 61. Any force tending to move the core toward the detonator would also act on the mass 59 and be resisted by the supporting pin and the finger 61 bearing against the head 42 which would resist the rotation of the mass 59 about the pin 58, and balance the tendency of the core to move.

The solenoid and core are substantially the same as solenoid 28 and core 29 and are numbered the same. The contact pin illustrated in FIG. 2 is journaled in plate 30 and beyond the plate it is reduced in diameter, at 62, and formed with a spear-like head 63. The reduced portion 62 supports a sleeve 64 of insulating material and is permanently connected to wire 65 of the solenoid and is in contact with spring finger 66. The spring finger 66 provides a ground to the housing which upon movement of the core engages the insulating sleeve and breaks the circuit.

The housing 56 is milled at 67 to form a recess in which the spring finger 66 is mounted and through which the electrical grounding connection to the solenoid is made. A

The modification shown in FIG. 2 operates on a single switch. The closing of switch 68 in the circuit energized by battery 69 energizes the solenoid through the pin and finger 66. Subsequent movement of the core drives the head 63 of the pin through the metallic lamina of the disk 52 and into engagement with the spring contact 51. Movement of the pin moves the sleeve 63 into contact with the spring finger 66 breaking the circuit which is restored through the contact 51, wires 23, and through the nipple to ground. In this modification of the invention, the arming and firing operations are accomplished by closing a single switch 68 while in that of FIG. 1 the detonator is first armed and later fired from a separate source of power.

The invention fills a very definite need in providing a shielded detonator which is safe against accidental ignition by electrostatic or electromagnetic energy.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. An igniting device comprising a housing, a solenoid disposed within said housing and having a moveable core, a contact pin mounted on said core and moveable therewith upon the energization of the solenoid, an electrically initiated detonator supported by said housing in the path of movement of the core mounted contact pin, and metal lic means completely surrounding and shielding said detonator from all electromagnetic radiation, said contact pin rupturing said shielding means and making conr 4 tact with said detonator upon ener-gization of said solenoid.

2. An igniting device according to claim 1 including means for energizing the solenoid and separate means for igniting the detonator.

3. An igniting device comprising a housing, a solenoid mounted in said housing, a moveable core in said solenoid, a contact making pin carried by said core and moveable therewith, a metallic nipple attached to said housing, a detonator attached to and wholly within said nipple, metal disks at each end of said nipple forming together with the nipple an enclosure completely surrounding said detonator, the metal disks and nipple shielding the detonator from electrostatic and electromagnetic energy, means energizing the solenoid to project the contact making pin through a predetermined one of said metal disks and into contact with the detonator, to arm said detonator, and means for igniting said detonator after the detonator has been armed.

4. An igniting device according to claim 3 including safety means preventing undesired movement caused by inertia of the core and its attached contact making pin.

5. An igniting device according to claim 3 including a spring for holding the core in normal inoperative position.

6. An igniting device according to claim 3 including insulating means for said contact making pin to prevent shorting when said pin has pierced said metal disk.

7. An electromagnetic radiation proof igniting device comprising a detonator, a fixed contact, a metallic shielding means completely enclosing and shielding from electromagnetic radiation said fixed contact and said detonator, said detonator being connected in electrical series circuit between said fixed contact and said shielding means, a source of potential, means connecting said shielding means to one side of said source of potential, a movable contact, means connecting said movable contact to the other side of said source of potential, electrically operated means for driving said movable contact through said shielding means and into contact with said fixed contact, insulating means on said movable contact for insulating said movable contact from said shielding means after movable contact has been driven therethrough.

8. The igniting device of claim 7 wherein said electrically operated means is a solenoid.

9. An electromagnetic radiation proof igniting device comprising a detonator, a first fixed contact, frangible metallic shielding means completely surrounding and shielding electromagnetic radiaiton said detonator and said contact, said detonator, said fixed contact, and said shielding means being connected in electrical series circuit, a second fixed contact, a movable contact, said movable contact initially engaging said second fixed contact, a source of potential, said second fixed contact and said shielding means being connected to one side of said source of potential, electrically operative means for driving said movable contact through said frangible shielding means and into contact with said first fixed contact, a switch, one side of said switch being connected to the other side of said source of potential, said electrically operating means being connected in series between the other side of said switch and said movable contact, insulating means on said movable contact for insulating said movable contact from said second fixed contact and said shielding means after said movable contact has been driven into contact with said first fixed contact whereby when said switch is closed said electrically operative means is connected across said source of potential through said switch, said movable contact and said second fixed contact to drive said movable contact through said shielding means and into contact with said fixed contact to connect said electrically operative means to said other side of said source of potential through said detonator.

10. .An electromagnetic radiation proof igniting device comprising a completely enclosed metallic chamber providing a shield from electromagnetic radiation, a contact plug supported within and insulated from said chamber, an electrically fired detonator supported within said chamber, said detonator being connected in series circuit between said contact plug and said chamber, a source of potential, one side of said source being connected to said metallic chamber whereby said contact plug, said detonator and said chamber are initially maintained at a point of constant potential, a contact pin supported without said chamber, driving means connected to said pin to drive said pin through a wall of said chamber and into contact with said plug, insulating means on said pin to insulate said pin from the wall of said chamber after said pin has been driven therethrough, said pin being connected to the other side of said source whereby when said pin is driven through the wall of said chamber and into contact with said plug, the potential from said source is applied across said detonator.

11. The igniting device of claim 10 wherein said driving means is an electromagnetic solenoid.

12. The igniting device of claim 11 including means for separately energizing said solenoid.

References Cited in the file of this patent UNITED STATES PATENTS 1,844,865 Schladt Feb. 9, 1932 1,987,912 Rady et a1. Jan. 15, 1935 2,344,178 Sparrow Mar. 14, 1944 2,737,890 Brode Mar. 13, 1956 2,918,001 Alford Dec. 22, 1959 2,957,415 Lazari Oct. 25, 1960 FOREIGN PATENTS 2,826 Great Britain 1885 

1. AN IGNITING DEVICE COMPRISING A HOUSING, A SOLENOID DISPOSED WITHIN SAID HOUSING AND HAVING A MOVEABLE CORE, A CONTACT PIN MOUNTED ON SAID CORE AND MOVEABLE THEREWITH UPON THE ENERGIZATION OF THE SOLENOID, AN ELECTRICALLY INITIATED DETONATOR SUPPORTED BY SAID HOUSING IN THE PATH OF MOVEMENT OF THE CORE MOUNTED CONTACT PIN, AND METAL 